21316355116805 has 54 divisors (see below), whose sum is σ = 31611021617682. Its totient is φ = 13756316985600.

The previous prime is 21316355116801. The next prime is 21316355116867. The reversal of 21316355116805 is 50861155361312.

It can be written as a sum of positive squares in 3 ways, for example, as 7139872578916 + 14176482537889 = 2672054^2 + 3765167^2 .

It is not a de Polignac number, because 21316355116805 - 2² = 21316355116801 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21316355116805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21316355116801) by changing a digit.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 1228528880 + ... + 1228546230.

Almost surely, 2^{21316355116805} is an apocalyptic number.

It is an amenable number.

21316355116805 is a deficient number, since it is larger than the sum of its proper divisors (10294666500877).

21316355116805 is an frugal number, since it uses more digits than its factorization.

21316355116805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34755 (or 17380 counting only the distinct ones).

The product of its (nonzero) digits is 648000, while the sum is 47.

The spelling of 21316355116805 in words is "twenty-one trillion, three hundred sixteen billion, three hundred fifty-five million, one hundred sixteen thousand, eight hundred five".